Brake drum



lbrake drums.

i. lift, l2

enana-ne nacer applicaties entretien-ye, teas. senat in, astma.

This invention relates to improvements in l'leretot'ore, bralre drums have been made ot either cast iron or lorv carbon deep-draw steel. These metals, as is known, are relatively easily corroded. `ls a result oit this corrosion, the drum not only becomes nnsightly, but is also seriously weakened, due to the oxidation of the iron structure. lln brake drums, oxidation is greatly accelerated due to the catalytic eilfeot ot the generated heat ot triction.

Prior to this time, relatively little attention has been paid to the problem ot increasing the etiiciency and' lite ot brake drums 'by renderingthem relatively non"-corrodible.

'lhe oxidation ot the vdrum may obtain not' only -Aon the exterior surface, which is exposed to moisture, but may also taire place on the interior ot the braking' itlange. rllhe possibility ot corrosion ot the braking flange will loe-mort readily appreciatedvvhen it is considered that, in certain types oi lining` materials are employed which are corrosive in action. For example, it the brake band had incorporated in it an appreciable amount ot a corrosive substance, such 'for example as sodium chloride, there would be a decided tendency to corrosion.

The maior object ot this invention is to provide a brake drum ot which they trictional surface is comprised et a metallic substance of relatively low corrodibility.

Another object is to provide a brake structure both the interior and eaterior surfaces ot `which `may be economically treated to lower the corrodibility.

the invention is illustrated diagrammatically in the single ligure ot the drawing.

ln the prior application' Serial llo. 274,675, tiled May il, 1928, there Wasdescribed a prod ess by which a terruginous hralre drum might bc cheaply treated to provide an exposed surface having an increased resistance to corrosion over that obtaining tor ordinary iron. rthe present invention is'concerned with this same general problem, but the increased resistance to corrosion is secured. by a ditterent method.

uhccording to the present invention, any

`the composition selected portion ot the braise drum be treated in a very simple and economical manner to change the physical properties ot that portion, among which is an increased resist0 ance to corrosion. llhe invention comprises the concept ot treating the drum so as to tornr as a constituent part ot the terrugin ous material a coating; or molecnlarly bonded skin oit a terroso-terric phosphate..

'lhe invention :may be edectnated by paru lrerizing any desired portion ot the drum. The parlrerizing process seems to be leased on the 'tact thatpliosphoric acid will react with iron to precipitate a terroirs phosphate on a metal surface. rlhe compound 1which is tormed'as a result ot theprocess appears to be a basic terroso-ierric phosphate and its action is to greatly increase the resistance to ordinary oxidation. v

rl`he particular manner ot' treating the drum may be Widely varied. its an example, the pre-termed drum may tirst be cleaned hy immersion in a suitable caustice tion, maintained at a temperature oit more or less. the drum is removed and vvashed "with hot Water and then is subjected to a piclrling in a tive-percent sulphuric acid pickle. Vlhe pickle bath preferably contains a small amount oit sodium iii-sulphate., its is lrnoivn,

oit the bath is such that sulphur di-ozride is upon the Work. llhe sulphur {li-oxide appar ently is generated to reduce some ot the dilli cultly soluble higher orioles ot iron to lovver oxides.

After the piclrling operation, the drum may then be immersed in the parlteriaing sou lution. 'the deposit ot the desired. phosphatic salt may be localized to any area by covering the portions which are not `treated with a suitable protective coating.

The treatin solution. may he made up by' treating;a iron ilings withconcentrated phoeplioric acid to prepare a paste ot 'ferrous phosphate. rthis paste may then be added to vfealr solution ot boiling phosphoric acid, in which is incorporated a suitable amount oit .an oaidiaing agent such as manganese cli-oxide.

'llllie drinn may be maintained in the 4heated soda soluiihitter cleaning, in the caustic, i

till

liberated and is 'tree to act bath for, say, from one to three hours, depending on the degree of protection desired. When the processing is completed, the drum may be removed and dried, and then dipped in` a 5 suitable oleaginous mixture.

It will be understood that there exists a wide range of choice in the particular processing solution which is employed. Forexample, the drum may be treated with a solution made up of phosphoric acid, sodium'dichromate and water or, if desired, the drum may be subjected to the action of a mist of phosphorus pentoxide in water vapor. Any such similar treatment which Will form a molecular skin or coating on the drum which comprises a compound having the protective features of a basicferroso-ferric phosphate may be employed.

As will be understood, the particular character of the coating may be somewhat varied by varying .the initial cleaning treatment. The character of the final coat will change somewhat, dependin@ upon whether the preliminary cleaning ofthe metal has been by sand blast, rubbing or pickling. i

.This method of treatment presents many advantages. The process, as such, is a very economical method of rendering a ferruginous article relatively non-corrodible. In addition to this, iron which is so treated has such a molecular structure as to render it particularly Well adapted as a base for special finishes of lacquers, paints or enamel. This is a feature of more than passin importance in the brake drum art, because o the fact that the exterior surface of the drum is, in most cases, colored with a suitable paint so as to harmonize with the color scheme of the car. Another advantage resides in the fact that the process, which appears essentially to be a precipitation of a reaction salt Within the pores of the metal, serves to fill up depressions or perforations and presents a smoother coating, and for this reason is particularly useful as a method of treating cast iron drums. The skin which is formed as a result of this treatment does not, of course, have the abrasion-resisting properties of a harder alloy steel. However, due to the facility and cheapness of the process, it may be economically employed not only on new drums but on those which have been subjected to rather extended use.

As pointed out hereinbefore, the treatment may be applied to any desired section of the drum. In the drawings, there is shown a brake drum the inner surface of which comprises a skin or ring molecularly bonded to the ferruginous foundation metal. This is particularly useful in a brake drum which is constructed for use with an internal band brake. However, it will be appreciated that both the interior and exterior surfaces of the braking fiange may be coated, or if desired, the envention is conceived to reside in the "tire drum may be provided with the protective coating.

While there has been described a particular treatment, it is to be understood that this is subject to Wide modification and it is to be understood that the invention is not limited to any particular type of treatment. The inprotection ofr a brake drum which comprises molecularly bonded metals and/or metallic compounds Which impart the desired characteristic of lowered corrodibility.

I claim:

l. A parkerized brake drum.

2. A brake drum comprising a fcrruginous foundation metal and a surface including a phosphatic salt of the foundation metal.

3. A brake drum comprising a ferruginous foundationnietal and a inolecularly bonded surface of an'inorganic salt of the foundation metal. y

4. A brake 'drum comprising a ferruginous foundation metal and an integral surface comprising a substance containing phosphorus.

5. A brake drum comprising a ferruginous foundation metal and a molecularly bonded inorganic salt of the foundation metal having a. lower corrodibility than the foundation metal.

(i. A brake drum comprising a fcrruginous foundation metal and a phosphatic salt molecularly bonded thereto.

7. A brake drum having a parkcrized braking flange.

8. A brake drum having a parker-ized cxy terior surface.

9. A brake drum having a parkerized frictional surface.

10. A brake drum comprising a ferruginous foundation metal and a surface thereon in which a phosphate is molecularly incorporated.

In testimony whereof I affix my signature.

RAYMOND J. N ORTON 

